import Text.Parsec
import Text.Parsec.Char
import Data.List

contain
  = do { num <- many1 digit;
         many1 space;
         x <- many1 letter;
         many1 space;
         y <- many1 letter;
         many1 space;
         if num == "1" then
           string "bag"
         else
           string "bags";
         return (x ++ " " ++ y, read num :: Integer);
       }

line
  = do { x <- many1 letter;
         many1 space;
         y <- many1 letter;
         many1 space;
         string "bags contain";
         many1 space;
         z <- do { rcar <- contain;
                   rcdr <- many $ (string "," >> many space >> contain);
                   return $ rcar:rcdr;
                 } <|> (string "no other bags" >> return []);
         char '.';
         return (x ++ " " ++ y, z)
       }

p
  = many1 $ line >>= \x -> many1 space >> return x

calc :: [(String, [(String, Integer)])]
     -> String
     -> Integer
calc dict target
  = case lookup target dict of
      Just lst -> sum $ map (\(s, i) -> i + i * calc dict s) lst
      Nothing -> error ""

main
  = readFile "7" >>= \x -> putStrLn $ case runParser p () "7" x of
                                        Left err -> show err
                                        Right x -> show $ calc x "shiny gold"